1. Field of the Invention
The present invention relates to a heat spreader, and more particularly to a heat spreader with an improved vapor chamber for reducing a thickness thereof.
2. Description of Related Art
It is well known that heat is generated during operations of electronic components, such as integrated circuit chips. To ensure normal and safe operations, cooling devices such as heat sinks are often employed to dissipate the generated heat away from these electronic components.
As progress continues to be made in the electronics art, more components on the same real estate generate more heat. The heat sinks used to cool these chips are accordingly made larger in order to possess a higher heat removal capacity, which causes the heat sinks to have a much larger footprint than the chips. Generally speaking, a heat sink is more effective when there is a uniform heat flux applied over an entire base of the heat sink. When a heat sink with a large base is attached to an integrated circuit chip with a much smaller contact area, there is significant resistance to the flow of heat to the other portions of the heat sink base which are not in direct contact with the chip.
A mechanism for overcoming the resistance to heat flow in a heat sink base is to attach a heat spreader to the heat sink base or directly make the heat sink base as a heat spreader. Conventionally, the heat spreader has a vacuum chamber defined therein, a wick layer provided in the chamber and formed allover inner faces of the chamber, and a working fluid contained in chamber and overflowing a part of the wick layer. As an integrated circuit chip is maintained in thermal contact with the heat spreader, the working fluid contained in the wick layer corresponding to a hot contacting location vaporizes. The vapor then spreads to fill the chamber, and wherever the vapor comes into contact with a cooler surface of the chamber, it releases its latent heat of vaporization and condenses. The condensate reflows to the hot contacting location via a capillary force generated by the wick layer. Thereafter, the condensate frequently vaporizes and condenses to form a circulation to thereby remove the heat generated by the chip.
Since the wick layer is distributed allover the inner faces of the heat spreader having a poor capability of storing liquid, a predetermined space should be formed inside the heat spreader to contain enough liquid therein. Thus, two parts of the wick layer formed on two opposite inner faces of the heat spreader have a distance defined therebetween to form the predetermined space. However, the distance would cause the heat spreader to be thick, and can not be mounted in a thin electronic device which has became a development tendency nowadays.
What is needed, therefore, is a heat dissipating device which can overcome the above-mentioned disadvantages.